The present invention relates to nuts and nut products, and particularly to an improved process for preparing reduced calorie nuts and nut products.
The term "nuts" as used in this description includes whole nuts, splits, and pieces of nuts such as peanuts, cashews, almonds, Brazil nuts, filberts, pecans, walnuts, and the like. For purposes of conciseness in description, the following disclosure will center around the production of low-fat peanuts. It is not intended, however, to be limited to peanuts because the principles which will apply for peanuts should apply to other nuts.
The basic procedures for preparing partially defatted nuts have been known for a number of years. For example, in U.S. Pat. Nos. 2,003,415 to Ammann and 3,294,549 to Vix et al., procedures for pressing the oil from nuts such as peanuts are described. Broadly, these methods include the steps of pressing nuts until the desired quantity of fully digestible triglyceride fats are removed and then steaming or cooking the partially defatted nuts in water until the nuts are reconstituted to substantially their original size and shape.
Both the Ammann and Vix et al. patents discuss the virtues of partially defatted nuts in the diet. It is the decrease of triglyceride fat level in partially defatted nuts that give them a significantly lower calorie content than full fat nuts. Further work on the process of Vix et al. is described in a series of articles entitled, "Development and Potential of Partially Defatted Peanuts," Peanut Journal and Nut World, January and February 1967, and an article entitled, "Low Calorie Peanuts", Food Processing/Marketing, September, 1965.
Later workers, encouraged by the apparent appeal of partially defatted nuts to weight-conscious consumers, continued to work in this area. U.S. Pat. No. 3,645,752 to Baxley discloses a process which "improves" the flavor of partially defatted nuts by quenching them in a flavored oil after roasting. Although such oil quenching may improve the flavor of partially defatted nuts, it also appears to restore them to a substantially full fat content.
U.S. Pat. No. 3,740,236 also to Baxley indicates that roasted peanut flavor is reduced in proportion to the percentage of the peanut oil removed during the pressing process. Baxley, however, does not prevent flavor loss but only attempts to improve flavor after it is diminished. This is achieved by reconstituting partially defatted nuts in an aqueous binder solution containing flavor.
The reason for the loss of flavor in partially defatted nuts is not fully understood. The Doctoral Dissertation of M. E. Mason, entitled "Procedures in Studying and Factors Influencing the Quality and Flavor of Roasted Peanuts", Oklahoma State University, 1963, pages 63 and 64, indicates that the triglyceride fat pressed from peanuts contains aleurone grains, among other particulates, which appear to contain flavor precursors. The Mason dissertation, however, is not concerned with the preparation of low-fat nuts, but simply with gaining a better knowledge of the source and identification of flavor principals in peanuts.
U.S. Pat. No. 4,049,833 to Gannis et al. also recognizes the adverse effect partially defatting nuts has on flavor and texture. To correct this, Gannis contacts partially defatted nuts with a glycerol-containing solution to reconstitute them before roasting.
U.S. Pat. No. 4,329,375 to Holloway et al. discloses a process for preparing low-fat nuts, such as peanuts, which retain more of their natural flavor and texture than products prepared by earlier procedures. This high quality product is achieved by pre-roasting the nuts to partially develop a roasted nut flavor and color, pressing only after equilibration of the internal nut moisture, and limiting the amount of oil extraction.
U.S. Pat. No. 4,466,987 to Wilkins et al. relates to the production of low fat nuts prepared by moistening, initially roasting, pressing, hydrating, and finally roasting.
Although the partially defatted nuts of Gannis, Holloway, and Wilkins represent vast improvements over those products prepared simply by pressing and then cooking with hot water or steam, all such nut products inherently lack the taste and mouthfeel of full fat nuts. This problem is, at least in part, due to the lower oil content of such nuts. It is also caused by the destruction of the nut microstructure during pressing. Such structural damage is not restored by mere roasting and reconstitution. As a result, roasted, partially defatted nuts lack the crunch of full fat nuts.